1. Field of the Invention
The invention relates to a wind energy collection system, and more particularly, the invention relates to systems and methods for collecting energy from wind and converting the wind energy to useful energy forms.
2. Brief Description of the Related Art
Many wind energy collection systems have been proposed in the prior art. Classic windmills and wind turbines employ vanes or propeller surfaces to engage a wind stream and convert the energy in the wind stream into rotation of a horizontal windmill shaft. These classic windmills with exposed rotating blades pose many technical, safety, environmental, noise, and aesthetic problems. The technical problems include mechanical stress, wind gusts and shadow shock, differential blade pitch control, active steering, and dynamic instability which may lead to material fatigue and catastrophic failure. In addition, the propeller blades can cause safety concerns and significant noise generation. Furthermore, these horizontal axis wind turbines cannot take advantage of high energy, high velocity winds because these winds can overload the turbines or the moving blade systems causing damage or failure. In fact, it is typical to shut down conventional horizontal windmills at wind speeds in excess of 35 mph to avoid these problems. Since wind energy increases as the cube of velocity, this represents a serious disadvantage in that high wind velocities which offer high available energies require that the windmills be shut down.
Vertical axis turbines are a more recent development. Although vertical axis turbines address many of the shortcomings of horizontal shaft windmills, they have their own inherent problems. Many vertical axis turbines are very large, employing towers hundreds of feet in the air. They are also expensive and have a significant aesthetic impact.
One alternative to the horizontal and vertical axis wind turbines described above is the airfoil wind energy collection system described in U.S. Pat. No. 5,709,419. This system provides the advantage that the parts of the system which contact the wind to collect energy do not employ moving parts. This wind energy collection system includes an airfoil or an array of airfoils with at least one venturi slot penetrating the surface of the airfoil at about the greatest cross-sectional width of the airfoil. As air moves over the airfoil from the leading edge to the trailing edge, a region of low pressure or reduced pressure is created adjacent the venturi slot. This low pressure region, caused by the Bernoulli principal, draws air from a supply duct within the airfoil out of the venturi slot and into the airflow around the airfoil. The air supply ducts within the airfoil are connected to a turbine causing the system to draw air through the turbine and out of the airfoil slots generating power.
It would be desirable to provide a wind energy collection system with non-moving wind contacting parts which provides improved efficiency and a stronger, simpler construction.